DETERMINATION OF 2-BUTOXYETHANOL AND BUTOXYACETIC ACID IN RAT AND HUMAN BLOOD BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A sensitive and selective gas chromatographic-negative-ion chemical ionization mass spectrometric method was developed to simultaneously quantitate 2-butoxyethanol (BE) and butoxyacetic acid (BAA) in rat and human blood at low ng/g levels as pentafluorobenzoyl and pentafluorobenzyl derivatives, respectively. Analysis of C-13-labeled analogs of BE and BAA were found to improve the limits of quantitation to below 2 ng/g. Deuterium-labeled BE and BAA were used as internal standards. Calibration curves were generally linear over three orders of magnitude, with limits of quantitation of 16-18 ng/g for both BE and BAA, and 1.5 and 0.4 ng/g for [C-13(2)]BE and [C-13(2)]BAA, respectively, in human blood. Linearity in rat blood was similar, with limits of quantitation of 22 ng/g for BE and 5 ng/g for BAA. This method was developed for the support of mammalian metabolism studies and human biomonitoring studies involving exposure to BE or [C-13(2)]BE.